Switch actuating device



June 25, 1968 c. B. KNuDsoN SWITCH ACTUATING DEVICE Filed Feb. 25, 1966 w M 2 w] n a Z W Mw c ma WM United States Patent() s Y 3,389,610 f v SWITCH ACTUATING DEVICE Clarence B. Knudson, 9627 2nd Ave.,

Inglewood, Calif.` 90305 Filed Feb. 23, 1966, Ser. No. 529,506

, -7 Claims. (Cl. 7442) as a consequence of which the switch can have different switch-open and switch-closed times.

Certain 'applications may require the switch or switches to be actuated in a cyclic manner, such as having a switcliclosed period of two units of time followed immediately 'by an open period of one unit of time, Iby way of example. Heretofore, this type of switching action has been provided by means of Aa cam having a special contour. Cam-operated devices have many problems associated therewith, such as non-uniform bearing and motor shaft loading, and excessive vbea-ring wear.

It is an object of the present invention, therefore, to provide a novel switch actuating device.

It is another object of the present invention to provide a switch actuating device that results in uniform bearing and motor shaft loading.v

Itis still another object of the present invention to provide a switch actuating device that causes a minimum of bearing wear.

It is yet another object of the present invention to provide a switch actuating ldevice that does not utilize a cam and which is adaptable for actuationv Iof either single pole single throw I(SPST) or single pole double throw (SPDT) mercury tilt switches.

According vto the preferred embodiment of the present invention, a switch actuating device is crank driven and has characteristics that make it uniquely suited for actuation of a mercury tilt switch. The device utilizes -a crank and a link instead of a cam to provide the mechanical motion required to tilt a mercury switch in a prescribed manner.

The features of the present invention which are believed to be nove-l are set forth with particularit'y in the appended claims. The present invention, both as to its organzation and manner of operation, together with further objects and advantages thereof, may -best be understood by reference to the following description, taken in con nection with the accompanying drawings, in which:

FIGURE l is a si-de view of a switch actuating device according to the present invention.

FIGURE 2 is a graph of rocker arm angular movement .plotted ag-ainst rotation of the driving shaft, for the device shown in FIGURE l.

Turning now to the drawings, FIGURE 1 shows crank 11 rigidly attached to shaft 13 of motor 15, so that crank 11 will rotate in a clockwise direction, as indicated by arrow 17. It is to be understood that other embodiments could utilize rotation in a counterclockwise direction.

One end of link 21 is pivotally connected to crank 11 by means of crank pin 23, and the other end of link 21 is pivotally connected to right-angle downward extension 24 at one end of rocker arm 25 by means of pivot pin 27. The distant end 28 of rocker arm 25 is pivotally con- 3,389,610 Patented June 25, 19678` ice nected to mounting plate 29 by means of pivot`pin 31. Rotary motion of crankl 1-1 is therefore converted to yarigular motion of rocker arm 25, ywhich is shown in a horizontal position by `way of example only. f

A suitable switch 33, such a a mercury tilt switch, is attached to rocker arm 25, and is actuated by the angular motion thereof. Spiral spring 35 is attached to the end, or hub, 28 of rocker arm 25 and the mounting Iplate 29 in Iorderto balance the load presented by the switch 33, thus minimizing variations in the driving torque. p

The present invention has been found to be particularly lwell suited to provide a switching means for use with obstruction warning lights commonly referred to as ashing beacons. Such beacons generally are required to be turned ON for -a period twice as llong as 4the OFF period, and the flashing isv repeated in a cyclic manner. It will be apparent from the following description of the mechanism action, that the operating cycle is .suitable for this application.

Referring now to FIGURE l, it `will be seen tha-t the various parts are shown in a particular relationship to eac-h other. The crank throw, length of link 21, length of rocker arm 25 and the relationship of pivot pins 27 and 31 to shaft 13 have ybeen proportioned in such a `way that movement of rocker arm 25 is slowed down during part of the operating cycle. Thus, pivot pin 27 lies farther from rocker arm 2'5 than does pivot pin 31, and when rocker arm 25 is horizontal, pivot pin 27 is not vertical with respect to shaft 13.

'FIGURE 2, which shows a plot of the rocker arm angular movement versus rotation of the driving crank, shows that movement of rocker arm 25 is slowed down during part of the operating cycle, The operating cycle is considered as starting at a time when the rocker arm is in a horizontal position. 'By reference to FIGURE 1, it will Ibe seen that clockwise crank movement relative to the zero or starting position, which is 12.5 ldegrees from the horizontal, will cause the rocker arm 25 and the switch 33 to be tilted upward. The tilt -increases as crank rotation continues and when point A of the curve 41 in FIG- URE 2 is reached, switch 33 will open.

Upward tilt increases as the crank 11 continues to rotate until a maximum is reached at a crank rotation angle of about 60 degrees, after which it starts to decrease as the crank 11 continues Ito move. lUpward tilt continues to decrease until the rocker arm again reaches a horizontal position. Further rotation of the crank 11 causes the rock-er arm 25 and the switch 33 to tilt downward. The tilt increases until point VB, shown on the curve 41 in FIGURE 2, is reached, at which point switch 33 closes. The downward tilt increases to a maximum and then starts to decrease as crank rotation continues until the rocker Varm 25 again is in a horizontal position, and the cycle is completed.

It will be noted by inspection of the curve in FIGURE 2 that the total angle of crank rotation required to move from point Ato point B is much smaller than the rotation angle required to move from point B back to point A of the next cycle. In the described embodiment the crank rotation angle from A to B is degrees, and from B to A of the next cycle it is 240 degrees. Thus, the switch-closed time is twice the switch-open time.

The unique non-linear action of the described rocker arm tilting mechanism causes slowdown in the rate of tilt angle change for crank positions from degrees to about 310 degrees of rotation. During this interval of time a very desirable settling of mercury in the switch takes place which appears to improve the switching action. The reduction in tilt angle achieved as a result of the slowdown action also aids in minimizing the sloshing of mercury in the switch. Linear movement of the rocker arm atdthe switch duces a positive jitter free switching action.

In one embodiment, the device is operated by means of a. motor with a gear reduction drive to actuate one SPST mercury tilt switch at a repetition rate of 30.times per minute. in another embodiment, the device, similarly operated, is utilized to actuate one SPDT mercury tilt switch 4for alternate application of power of the loads. The Vduty cycle shown in FIGURE 2 is incorporatedrand operation of the switch is such that power is applied to one load during the interval from A to B (one-third of the cycle), and to the other load during the interval from B back to A (two-thirds of thecycle).

It is to be understood that application of the described mechanical motion is notlimited to use with a single switch or for that matter with a mercury tilt switchfThe crank arm may be extended in order to operate several switches simultaneously. A multiple throw crankshaft also may be utilized with cranks arranged to provide various sequences in the operation of several switches.

While particular embodiments of the present invention ha-ve been shown and described, it will be obvious to those skilledin the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. A switch actuating device comprising:

(a) mounting means,

(b) support means adapted to support a switch, said support means being pivotally coupled to said mounting means,

(c) link means having a first region pivotally coupled to said support means,

(d) crank means having a first region pivotally coupled to a second region of said link means, said support means being horizontal when said crank means is in a first position, and

(e) a motor having a shaft fxedly connected to a second region of said crank means, said support means again being horizontal when said crank means makeand brake pointsl vpro-V is rotated by said, motor intoaseond position, the

angular motion of said support means when said crank means moves .from said first position to said second position differing from the angular motion of said support means when said crank means moves from said second position back to said first position. 2. Apparatus as defined in claim 1 including, in addition, spring means coupling said L.support means to said mounting means. 1'

3. Apparatus as defined in claim 2 in which said spring is a spiral spring.

4. Apparatus as defined in claim Y1 in which said first position of' said crank means is not horizontal.

5. vApparatus as defined in claimy 1 in which said support means is pivotally connected to said mounting means by a first pivot pin, said first region of said link means is pivotally connected to said-support means by Va second pivot pin, and when said support means is horizontal, said first and second pivot pins are not horizontal with respect to each other.

6. Apparatus as defined in claim 5 in which said sec.- ond region of said link means is pivotally connected to said crank means by a third pivot pin, and in which when said third pivot pin is vertical with respect to said motor shaft, said second pivot pin isv notv vertical with respect thereto.

7. Apparatus as defined in claim 5 in which Said second pivot pin is not vertical with respect to said shaft when said support means is horizontal. l

References Cited UNITED STATES PATENTS 2,243,679 5/1941' Overstrom et al. 2,558,140 6/1951 Kruzik 74-42 2,635,446 4/1953 smith 68-.12

` FOREIGN PATENTS 872,969 3/1942 France.

FRED C. MATTERN, JR., Primary Examinar.

MILTON KAUFMAN, Examiner. W. vS. RATLIFF, Assistant Examiner. 

